Are Ericoid Mycorrhizas a Factor in the Success of Calluna vulgaris Heathland Restoration? Anita Diaz, 1,2 Iain Green, 1 Marianne Benvenuto, 1 and Mark Tibbett 3 Abstract Methods used in the restoration of lowland heath vary de- pending on edaphic factors at a site and need for introduc- tion of ericaceous propagules. This study investigates the effect of some methods on growth of an important erica- ceous species, Heather (Calluna vulgaris). It also explores whether success of growth of C. vulgaris in restoration schemes is affected by its degree of colonization by ericoid mycorrhizal fungi (ERM). The success of Heather growth was compared at three sites, a control area of natural heathland and two restoration sites. These were a quarry where soil had been translocated but not chemically manipulated and a site on agricultural land where the top soil had been improved but then either stripped away or acidified prior to attempting heathland restoration. Propa- gules of C. vulgaris were applied either as turves or as clippings. Results show that clippings produced as dense a cover of C. vulgaris as turves over a period of 13 years and that plants in such swards can exhibit a degree of ERM colonization comparable to that found in mature plants growing in natural heathland. Young (<2 years of age) plants of C. vulgaris had less extensive mycorrhizal colonization of their roots, particularly when growing on restored agricultural soils. A relationship was found between lower levels of mycorrhizal colonization and smaller aboveground plant growth. Success of heathland restoration may be improved by finding means to enhance the rate and extent of mycorrhizal colonization of young C. vulgaris growing in a restoration environment. Key words: creation, habitat heath, mycorrhiza, restora- tion ecology, symbiosis. Introduction The decline in abundance and contiguity of British low- land heath during the past few centuries has been well documented (Gimingham 1972; Webb 1986, 1990; Farrell 1993). One of the most important causes has been land change due to agricultural intensification (Moore 1962; Webb & Haskins 1980; Webb 1990). The restoration of lowland heath is now a United Kingdom Biodiversity Action Plan priority (DOE 1995a, 1995b), and there has been a particular interest in the methods for the restora- tion of heathland on improved agricultural land. Early work identified that the conversion of heathland to agri- culture caused persistent changes in soil chemistry and physical structure (Marrs 1985) and that successful heath- land restoration was likely to require some form of amendment to the soils in order to reduce pH and nutrient availability (Marrs & Gough 1989; Marrs 1993; Pywell et al. 1994). A number of techniques have been used to attempt to achieve this such as soil stripping (Werger et al. 1985; Smith et al. 1991; Aerts et al. 1995) and soil acidifica- tion techniques including the addition of elemental sulfur (Chambers et al. 1996; Williams et al. 1996; Owen et al. 1999; Owen & Marrs 2000; Lawson et al. 2004; Tibbett & Diaz 2005). Heathland restoration on improved agricultural land often involves not only soil amendment but also the addition of heathland propagules either as translocated cut-turves of heathland (Pywell et al. 1995) or as clippings collected from mown heathland (Pywell et al. 1995, 1996; Owen & Marrs 2000; Lawson et al. 2004). The most abun- dant ericaceous species growing on United Kingdom dry heathland is usually Calluna vulgaris (L.) Hull (common name includes Heather and Ling) (Rodwell 1991). This species is known to be colonized by species of ericoid mycorrhizal fungi (ERM) (Kerley & Read 1997; Johansson 2001). Like other ericaceous species, the community of mycorrhizal species that colonize C. vulgaris may vary in the nature of their association; identifying the specific species involved is difficult as identification requires re- productive structures and the fungi tend to remain asexual in culture (Johansson 2001). However, one species, Hyme- noscyphus ericae (Read) Korf & Kernan, is commonly cited as forming mycorrhizal associations with ericaceous species including C. vulgaris (Johansson 2001). This sym- biosis is reported to increase the growth rate of C. vulgaris, particularly when growing in nutrient-poor soils where they enhance the plant’s nutrient acquisition (Strandberg & Johansson 1999). It is currently unknown whether colonization of C. vul- garis by ERM affects the success of heathland restoration 1 Centre for Ecology and Conservation Biology, School of Conservation Sciences, Bournemouth University, Dorset House, Talbot Campus, Fern Barrow, Poole Dorset BH12 5BB, U.K. 2 Address correspondence to A. Diaz, email adiaz@bmth.ac.uk 3 Centre for Land Rehabilitation, School of Earth and Geographical Sciences, Faculty of Natural and Agricultural Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia Ó 2006 Society for Ecological Restoration International JUNE 2006 Restoration Ecology Vol. 14, No. 2, pp. 187–195 187